Tellurium distribution and concentration in hydrometallurgical recovery of dust from annealing of nickel concentrate

Tellurium is a critically important element for developing society, and its need is growing. Over 90% of tellurium is produced from electrolytic sludge, but due to the transfer to hydrometallurgical technologies, it is currently relevant to extract tellurium from other intermediate products of metallurgy. The authors studied a tellurium distribution in the recovery process flow chart for dusts from annealing nickel concentrate applicable at the Severonickel works of JSC Kola Mining and Metallurgical Company. It has been determined that a main volume of tellurium is transferred to the water leaching solution used at the stage of the lead cake deposition. As a result, the cake contains up to 5%wt. of tellurium, which was separated from the sulfate phase of lead by chloride leaching to produce the concentrate. It is feasible to extract tellurium at earlier stages of dust recovery. The paper presents studies on the opportunity of tellurium concentration from the solution of water leaching of dusts by sorption and precipitation methods. Some ionites of the Purolite grade were tested for the sorption extraction, and showed efficiency of using chelating ionite Purolite S910 to extract 99% of the element.  The authors studied tellurium precipitation from solutions containing nickel, copper and iron. Iron-containing reagent precipitation contributed to not only deep refining from tellurium, but also production of the concentrate containing about 20% Te. Such concentrate can be supplied to produce high pure metal as part of the production at the Nornickel Concern. The solutions cleaned by sorption or precipitation are suitable for using both in the dust recovery process and main nickel production.